A coin processing device, which determines genuineness of inserted coins and sorts and stores coins determined as genuine coins for each denomination, is mounted inside a vending machine or the like. Such a coin processing device is provided with a coin sorting unit that determines the genuineness of the inserted coins and sorts out the coins for each denomination.
The coin sorting unit is provided with an outer diameter detection sensor that mainly detects an outer diameter of a coin and a material detection sensor that mainly detects a material of the coin. The outer diameter detection sensor includes a coil provided in a coin passage through which the inserted coin passes and is connected to an oscillation circuit. The material detection sensor is configured in the same manner. The oscillation circuit oscillates at an oscillation frequency depending on an inductance of the coil. This oscillation frequency is set to a frequency at which an electromagnetic field caused by oscillation is easily affected by the coin. As the electromagnetic field is affected by the coin, an amplitude of an oscillation signal also changes. Therefore, it is possible to detect the outer diameter and the material of the coin based on the oscillation frequency and the voltage. Accordingly, it is possible to perform genuineness determination and type determination of the coin.
Meanwhile, there is a coin processing device configured to determine genuineness of a plurality types of coins including a bimetal coin. The bimetal coin is a coin having different materials between a central core section and a ring section that surrounds the core section. For example, a two-dollar coin in Canada is known as the bimetal coin. In order to accurately detect an outer diameter of such a bimetal coin, a technique of using a ring-shaped outer diameter detection sensor having a space at the central section is known (see Patent Literature 1).
In the ring-shaped outer diameter detection sensor, a core section of the bimetal coin and the space of the outer diameter detection sensor overlap each other, and thus, an electromagnetic field (magnetic flux density) at the core section of the bimetal coin at this time is sufficiently smaller than an electromagnetic field at a ring section. Accordingly, it is possible to detect an outer diameter of the bimetal coin with high accuracy by mainly reflecting influence of the ring section at the outer circumference of the bimetal coin.